<!DOCTYPE html>
<html lang="zh-Hans">

<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge, chrome=1" />
    <meta name="viewport"
        content="width=device-width, initial-scale=1.0,maximum-scale=1,minimum-scale=1,user-scalable=no">

    <style>
        :root {
            background-color: red;
        }
    </style>
</head>

<body>
    <h1>我是一个内嵌网页,用于展示root伪类</h1>
</body>

</html>